1. Technical Field
The present invention relates to a nucleic acid polymer decomposition method and decomposition apparatus for decomposing a specific site of a nucleic acid polymer.
2. Related Art
Examples of conventional methods of decomposing specific sites of nucleic acid polymers such as DNA and RNA include methods that involve the cleavage of specific sites within DNA using restriction enzymes. These restriction enzymes are mainly enzymes that catalyze the site-specific cleavage of double-stranded DNA, and all of the DNA cleavage operations proceed via hydrolysis of phosphate diester bonds. Furthermore, DNA ligase can be used to freely bond cleavage fragments with other DNA fragments.
Furthermore, methods of cleaving DNA at specific sites using chemically synthesized molecules are also conventional. For example, National Stage Laid-Open No. Hei 10-508581 based on PCT/US95/12312 discloses a method in which a texaphyrin is used as the chemically synthesized molecule, and this texaphyrin is covalently bonded to an oligonucleotide, thereby enabling site-specific cleavage of DNA. In this case, the DNA cleavage is a photolytic cleavage. The cleavage is thought to be neither a hydrolysis (in which a water molecule is added across the bond causing the bond to break), nor a simple oxidation (in which an oxidation reaction causes the bond breakage in the absence of light). At present, details relating to the mechanism of the cleavage remain unclear.
Furthermore, methods of cleaving DNA at specific sites using ribozymes are also conventional. For example, National Stage Laid-Open No. Hei 10-508181 based on PCT/US95/02816 discloses a method in which any RNA can be targeted for specific cleavage by RNase P derived from prokaryotic or eukaryotic cells using a suitably designed oligonucleotide, namely an external guide sequence, to form a hybrid with the target RNA. This method is useful in preventing expression of the function of the target RNA, and in preventing the expression of disease or disorder-causing genes in vivo. Furthermore, with this method, in the same manner as was described above for nucleic acid cleavage using restriction enzymes, all DNA cleavages proceed via hydrolysis of phosphate diester bonds, and DNA ligase can be used to freely bond cleavage fragments with other DNA fragments.
However, with DNA cleavage methods that use restriction enzymes, the cleavage site is a DNA sequence site determined in advance by the nature of the enzyme, and cleavage at any position is problematic. Furthermore, temporospatial control of nucleic acid cleavage by enzymes is also difficult. Moreover, in those cases where the base at the RNA cleavage site has been modified by methylation or the like, the efficiency of the cleavage deteriorates.
Furthermore, in the method of Japanese Publication of unexamined PCT Patent Application No. Hei 10-508581 based on PCT/US95/12312, temporospatial control of the enzyme-based nucleic acid cleavage is difficult.
In addition, in the method of National Stage Laid-Open No. Hei 10-508181 based on PCT/US95/02816, the cleavage by a ribozyme is also a cleavage by an enzyme, and consequently, in the same manner as that observed for nucleic acid cleavage by restriction enzymes, temporospatial control is difficult. Furthermore, in the same manner as that observed for nucleic acid cleavage by restriction enzymes, cleavage by a ribozyme also suffers from a deterioration in the cleavage efficiency if the base at the DNA or RNA cleavage site has been modified by methylation or the like.